Duplicating collections in 2.81 not copying everything
The parented text object is actually missing even from the .001 collection (it's grayed out).
So it won't get duplicated.

How it happens
When you move parented (child) object into another collection, the parent relationship gets broken.
The child object icon will be grayed out, so you know it's broken.

And broken relationship doesn't get duplicated.

Solution
Find your parented text object, and move it back into the .001 Collection.
Then it will reconnect and will be duplicated with the parent.

Moving a parented object into a different collection breaks the relationship.
Moving it back reconnects it.